Q: My 88-year-old father lives in his own home about 100 miles from us. He’s been living alone since my mother died five years ago. I thought he looked rather thin last time we saw him. I’m starting to feel worried about his nutrition. Should I be concerned? Would you recommend he start drinking a supplement such as Boost or Ensure?

A: This question comes up a lot for families. It is indeed very common for older adults to experience unintentional weight loss at some point in late life.

The brief answer is that yes, you should be concerned. But I wouldn’t recommend you jump to purchasing Boost or Ensure.

Now, in most cases, some nutritional supplementation is in order. But before focusing on this, you should first get help figuring out why your father is losing weight.

For doctors, unintended weight loss is a major red flag when it comes to the health of an older person. So in geriatrics, we usually recommend that an older person — or his or her caregivers — monitor weight regularly. This enables us to spot weight loss sooner rather than later.

Once we’ve spotted unintentional weight loss, the next step is to figure out what might be causing it. And then we’re in a better position to recommend a treatment plan, which might well include a nutritional supplement.

Why You Should Monitor for Unintentional Weight Loss

This often goes hand-in-hand with malnutrition in aging. They aren’t quite the same thing: it’s possible to be malnourished without obviously losing weight. But they tend to go together. One study found that 39 percent of hospitalized older adults were malnourished.

It’s important to detect and evaluate weight loss and malnutrition for several key reasons:

They are often caused by underlying health problemswhich need to be diagnosed and managed.

They leave older adults weakened and more vulnerableto additional illnesses and injuries.

They may be a sign that an older person is impaired, or otherwise needs more support with daily life.

Fortunately, there’s an easy way to screen for these problems: tracking an older person’s weight.

How to Track Weight and Nutrition in an Older Person

Tracking weight: This is a terrific quick-and-easy way to monitor overall health and nutrition in an older adult. I usually recommend checking and recording the weight at least once a month.

(Note that nursing homes are usually required to weigh residents monthly; some assisted-living facilities may do so as well.)

You should keep records of the weight checks, preferably in a way that makes it easy to bring the information to the doctor’s office. Some families keep the information in a paper chart, but it’s potentially better to keep it in a shared computer file; see this article on keeping and organizing information for more details.

You can also consider one of the newer “connected” scales. These are devices that can wirelessly connect to a mobile device or even the home’s wifi. The weight record can then be accessed through an app or website.

Once you start tracking weight, at what point should you be concerned?

A general rule of thumb is that unintentionally losing 5 percent of one’s original body weight over three to six months is cause for concern. But it’s also reasonable to be worried if you notice a steady downward trend.

Tracking nutrition: Monitoring for unintended weight loss, as detailed above, is probably the easiest way to screen for nutrition problems.

Common Causes of Weight Loss and Malnutrition

It’s important for an older person to get a clinical evaluation once you’ve noticed weight loss or other signs of possible malnutrition. A simple screening tool that many clinics will use is the Mini Nutritional Assessment.

Neurologic disorders,including those that interfere with swallowing (2 to 7 percent)

Medication side-effects (about 2 percent)

Unknownafter extensive evaluation (10 to 36 percent).

Some additional issues that come up particularly in older adults include:

Difficulty leaving the house to purchase food. This can be due to limited mobility (e.g. due to pain, fear of falling, etc.), lack of transportation or cognitive problems.

Difficulty affording food. Some older adults live on a very limited income.

Difficulty or pain with chewing and swallowing.Many older adults fall behind on dental care for various reasons. This can lead to painful mouth conditions or a lack of suitable dentures.

Constipation. This is quite common in older adults and can interfere with appetite and eating enough.

Paranoia about food, due to dementia or a psychiatric condition. A fair number of older adults become suspicious of others during early dementia. Occasionally this leads them to not eat enough.

Forgetting to eat or having difficulty organizing meal preparation. This is especially common for those with Alzheimer’s and other dementias, but can also be due to problems like depression or even mobility limitations.

Unappetizing food. Sometimes the food is not to an older person’s taste, especially if it is a low-salt, low-fat, low-carb, low-sugar, or other medically “recommended” diet.

What Doctors Want to Know

To sort through all these possibilities, doctors will need to interview the older patient and the family. They will want to know:

How is the older person’s appetite? Do they like to eat or seem uninterested? How has this changed over the past year?

Any pain or difficulty with chewing or swallowing?

Any problems with nausea, vomiting, or feeling full easily? Any abdominal pain?

Any problems with diarrhea or constipation?

Who does the shopping for food? Who cooks the meal and organizes the time to eat? Does the older person do this alone or usually with someone else involved?

It’s also very helpful for the doctors to have as much information on what food — and how much food — the person is actually eating.

Last but not least, during the clinical evaluation, the doctor will physically examine the older person and then probably order some bloodwork as well.

How to ‘Treat’ Unintentional Weight Loss

The best treatment plans are based on a careful evaluation and correct diagnosis of what health problems — and social factors — are causing the weight loss.

Unfortunately, it’s common for many doctors to quickly turn to prescribing high-calorie supplements like Ensure, or even prescription appetite stimulants. In fact, this is such a common problem that the American Geriatrics Society chose to address it in its Choosing Wisely recommendations:

“Avoid using prescription appetite stimulants or high-calorie supplements for treatment of anorexia (loss of appetite) or cachexia (loss of muscle mass) in older adults,” the recommendations say. “Instead, optimize social supports, discontinue medications that may interfere with eating, provide appealing food and feeding assistance, and clarify patient goals and expectations.”

Even when social issues and medical problems are addressed, it’s often necessary to provide some extra nutritional support to those older adults who have been losing weight.

This usually means providing extra protein and extra calories. Fat is dense in calories, so this can be a good way to increase energy intake. Technically it’s better to provide “good fat” like olive oil, but in the short-term, I encourage people to consider whatever fatty foods the older person really likes to eat, which might mean ice cream or peanut butter.

So should you consider Ensure or Boost? You should discuss more with your parent’s doctor, but my take is that such commercial supplements should be used only as a last resort. They are expensive, usually contain a lot of sugar, and contain various additives. It’s better to make your own smoothies or otherwise provide nutrient-dense snacks and protein, if at all possible.